The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art.
Generally, an automatic transmission uses a hydraulic actuator with piston positioned between a pair of cylinders filled with hydraulic fluid to operate clutches. A spring pack operates as a return spring and is positioned on the back surface of the piston. The rotational movement of the hydraulic fluid creates centrifugal forces that increase the pressure in each cylinder. Whether the clutch is engaged or unengaged, ideally, the pressures in the two cylinders resulting from the centrifugal forces are approximately equal such that the spring pack is able to apply a sufficient return force to the piston to keep in the unengaged position or move the piston back to the unengaged position. At start up, however, the pressure in the cylinder on the front side of the piston typically exceeds the pressure on the back side of the piston since the volume of the cylinder on the front side the piston is typically smaller than that of the cylinder on the back side of the piston.
Accordingly, to maximize the utility of the spring pack, it is desirable to minimize the cylinder volume on the back side of the piston.